The anxiety demonstrated by Anna, summoned to her boss's office without explanation, will be familiar to any corporate worker. That she works for a government agency in the 1930s Soviet Union — an agency where the last director disappeared without warning — enhances her fear.

This is the opening to John W. Lowell's "The Letters," onstage at Mad Cow Theatre. It's a nifty piece of thoughtful entertainment that after a slow first five minutes or so, grabs your brain and won't let go. Anna and her boss, known as the Director, are the only characters onstage — though Lowell's descriptive writing brings two unseen workers in Anna's department vividly to life.

Those two others — a "departmental fixture" long passed over for promotion, and an eager if somewhat unreliable newcomer to the ministry — have a part to play in the reason for Anna's unexpected meeting. That reason gradually becomes clear as Lowell's plot unfolds like a mystery novel, with a clue dropped here, a hint there.

Blake Braswell, directing his first play at Mad Cow, gets sharp performances from his stars. Brian Brightman's Director goes from charming to ferocious in a flash, keeping Anna off-balance. Even as he straightens a photo of Stalin or pins the communist hammer-and-sickle emblem on his lapel, he keeps the audience guessing as to where his sympathies lie.

As Anna, Jennifer Christa Palmer delights as moments of shrewdness and the occasional spunky comment, all tempered with a desperately controlled fear, show there's more than meets the eye to this mild-mannered office drone.

Braswell makes good use of the space in Mad Cow's smaller theater. His actors circle each other, as if they're trapped in a cage. Lisa Buck's scenic design brilliantly captures the strange juxtaposition of rich and poor in the post-revolution Soviet Union. The Director's grand semi-circular carved wooden desk sits ostentatiously near beat-up industrial file cabinets and ragged-looking window blinds.

But Lowell's not making a statement about politics here. While his Soviet-set play can conveniently let red-blooded Americans feel smug about freedom and individualism and the fall of communism, it's hard to stop our own government's recent surveillance scandal from coming to mind.

"Guiltless people have nothing to fear from a little scrutiny," the Director rasps with an oily grin. It seems equally believable that statement could be made by a 1930s Soviet functionary or a 2014 National Security Agency spokesman.

No, Lowell's clever and engrossing play is making a statement about the human condition, how we mentally cope with a job, and a world, that leave us feeling powerless — no matter what emblem we pin on our lapel.